Robotic work tools, such as lawnmowers and in particular automatic lawnmowers, may be provided with a skid plate for protecting critical components arranged on the underside of the robotic work tool. For example, during operation rotating cutting discs may cause rocks present in the ground to accelerate upwards, and towards expensive parts arranged within the mower such as reduction gears, motors, etc. Other work tools being suspended by means of shock absorbers or similar may allow the underside of the work tool to come into contact with the ground e.g. when passing obstacles.
The skid plate is for this purpose provided on the underside of the work tool, forming a protective cover for the work tool. The skid plate is normally manufactured by a non-abrasive material in order to withstand impact from various objects present in the operating area of the work tool.
It is known to attach the skid plate to the underside via a hub, whereby the skid plate covers the hub and extends radially outwards from the hub. The hub also forms a fixed support to a rotatable cutting disc of the work tool; since the rotatable cutting disc extends radially out from a driven rotational shaft, the driven shaft is supported by the skid plate hub by means of two bearings.
Hence the skid plate hub is stationary, while the driven shaft is allowed to rotate relative the skid plate hub due to the provision of the two bearings.
The skid plate is attached to the hub by means of a number of screws, being insertable into associated threaded recesses of the hub for securing the position of the skid plate. The screws must be inserted into the hub, thus significantly reducing the available space for the bearings. A certain axial distance between the two bearings is often necessary in order to ensure sufficient life time of the bearings as well as a reduced noise level. The surrounding environment for the cutting equipment is very tough with grass, dust and water. To increase the lifetime of the bearings, it is important to seal the space around the bearings.
There is thus a need for a robotic work tool system that is able to overcome the above mentioned disadvantages.